Assisted-listening devices, e.g., hearing aids and the like, should be capable of operating in, and being adaptable to, several environmental conditions. For example, the assisted-listening device should to be capable of automatically selecting amongst various audio sources, e.g., telecoil, microphone, or auxiliary. One commercially available hearing aid utilizes a magnetic reed switch to provide magnetic field detection and automatic transducer mode selection. Unfortunately, there are a number of limitations associated with utilizing the magnetic reed switch. Frequently, the reed switch lacks the sensitivity to operate with many types of telephones and often requires placing an external magnet onto the telephone handset earpiece. Additionally, the reed switch requires use of a portion of the communicate device, such as a very limited space within the hearing aid. Furthermore, the reed switch may be susceptible to damage or performance changes if the hearing aid is dropped or subjected to extremely high magnetic fields—thus undermining the effective reliability of the assisted-listening system. Another shortcoming involves the added costs that are incurred to implement the reed switch into the assisted-listening system due to the additional components and manufacturing effort required.